3D B-field sensor

The B-field sensor was originally designed for the D-zero project in the late nineteennineties. It uses three hall-sensors,orthogonally placed, to measure the magnetic field strength and direction. It includes a temperature sensor to compensate the Hall-measurements for temperature effects. The sensors were connected to the conditioner via flat cables. The conditioner is read and set-up via an SPI bus to a CAN interface. The description.
For Atlas the the sensor and conditioner were integrated onto one PCB, see below. Schematic. This is connected to a CAN node, also used for temperature measurements and detector controls. Two of these sensor boards can be connected via one flat cable. Two flat cables can be connected to the ELMB.
There are a few versions in use, for different field strengths. In 2008 the PCB was redesigned for a number of reasons:

The board had to be ported to a new CAD tool.
We tried to lower the noise further, by minor changes in the design.
We added a new addressing scheme, while keeping it compatible with the Atlas configuration. It also had to remain compatible with the calibration set-up at CERN.

A small plug-on CAN node was developed thus allowing a larger number of sensors on a (long) cable, the BatCAN. It is based on an Atmel microcontroller.
An other plug-on board supports the use of normal flat cable instead of the user unfriendly cable needed before: SimBad. It also supports broadcasts in the new addressing scheme. This new scheme uses a one wire protocol for addressing, but the hardware implementation allows broadcasts also. The data exchange (set-up and read-out) is still SPI. User documentation.
The latest development is a CAN module that will support four of these strings and will be able to apply the calibration parameters locally, instead of doing so off-line.

B-sensor types
Cable specifications/ descriptions
The CANopen software description
The CERN power supply
BatCAN, a plug-on board to crate a CAN node directly at the sensor
SimBad, a SImple B-field sensor ADaptor for standard flat cable
BROCC (B-sensor Read-out Controller with Can interface), an ARM based interface that supports up to four strings of sensors and has a CAN interface

The picture at the right is one of the various types build

For questions about hardware contact Jaap Kuijt
For questions about software contact Henk Boterenbrood
You can mail

suggestions for this page to: Henk Groenstege.

April 2009